Bridges

[Cody J]

I'm looking for curved bridges. They need to fit 22" radius Atlas code 83 track. I would like them to be pre-built. I've looked around on hobbylinc.com and couldn't find any curved bridges. Any ideas?

Thanks,
Cody

[ABC]

I think you'll have to build one from a kit.

[Cody J]

I'm going to use these:

http://www.hobbylinc.com/htm/atl/atl80.htm

The creek isn't going to be very wide so I can use one of a size then use the other where the tracks cross the creek again.

[ebtnut]

Just as a general note, up until about the 1990's, all railroad bridges were straight.  What I mean by that is that the bridge structure itself had no curved segments.  The engineering computations for the stresses were just too complicated without computers.  Now, the track on the bridge might be curved; if it was, then the bridge might have to be widened to accommodate the overhang of the rolling stock.  Highway bridges were essentially in the same boat - the bridge structure was straight, even if the pavement surface that it supported was curved. 

[sparkyjay31]

Curved side to side?  If so try searching on eBay.  I recall not too long ago seeing a trestle curved bridge.  It was handmade, and not cheap.  Might suit you nicely.

[Cody J]

Thanks, Sparky but I'm just going to get a little pier made by Atlas. It's only for a creek so it's not going to be very wide so the pier will fit me nicely

[jward]

a simple way to make a bridge on a curve is to take an atlas plate girder bridge and turn it upside down. you then lay your curved track across what would normally be the bottom.

[barrowsr]

Jeff,

The upside down plate girder is a good idea but will probably give Cody an ovehead clearance problem with the track below.  Cody, how about using the plate girder bridge right side up and just widening the sides enough to accomodate your 22 inch radius curve?

Robin

[Cody J]

That's a good idea. And I had thought about that but then I realized that It was 9 inches long and the only 9" straights I have were either along the yard or along the industrial areas. I'm just going to use the piers because it's cheaper then the 2 bridges and it's easier than widening two bridges

[BaltoOhioRRfan]

Just as a general note, up until about the 1990's, all railroad bridges were straight.  What I mean by that is that the bridge structure itself had no curved segments.  The engineering computations for the stresses were just too complicated without computers.  Now, the track on the bridge might be curved; if it was, then the bridge might have to be widened to accommodate the overhang of the rolling stock.  Highway bridges were essentially in the same boat - the bridge structure was straight, even if the pavement surface that it supported was curved. 

I believe the B&O had a curved "Bridge" (I think, not sure waht a diffrence between a viaduct and bridge are, both look the same to me) that was built ages ago in the 1800's! The Thomas Viaduct. Still in active use today.

[ebtnut]

Re:  The Thomas Viaduct, I think if you inspect it closely you will find that each arch segment is straight.  The bridge engineers would have inserted an extra course of stone on the outside of the bridge to fill in the gaps caused by the curve.  The parapet stones at the top of the bridge would be laid in a curve to match the track, but they aren't part of the support structure.  BTW, the Thomas Viaduct was built in the 1830's, and is the oldest railroad bridge in service in the country.

[ryeguyisme]

Curved bridges only make me think Trestles or Commuter lines

[BaltoOhioRRfan]

Re:  The Thomas Viaduct, I think if you inspect it closely you will find that each arch segment is straight.  The bridge engineers would have inserted an extra course of stone on the outside of the bridge to fill in the gaps caused by the curve.  The parapet stones at the top of the bridge would be laid in a curve to match the track, but they aren't part of the support structure.  BTW, the Thomas Viaduct was built in the 1830's, and is the oldest railroad bridge in service in the country.

Not true, there is one thats a bit older thats still in active service on the "Old Main Line" the Carrollton Viaduct is a year older.

[Doneldon]

I used an Atlas truss bridge, right side up, but with a sheet of mild steel to widen the right of way.  Then I trimmed the corners to fit in with the adjacent terrain.